Liquid-phase syntheses of sulfide electrolytes for all-solid-state lithium battery

Solid sulfide electrolytes are key materials in all-solid-state lithium batteries because of their high lithium-ion conductivity and deformability, which enable the lithium-ion path to be connected between the material’s grain boundaries under pressure near room temperature. However, sulfur species are moisture-sensitive and exhibit high vapour pressures; therefore, syntheses of sulfide electrolytes need to be carefully designed. Liquid-phase reactions can be performed at low temperatures in controlled atmospheres, opening up the prospect of scalable processes for the preparation of sulfide electrolytes. Here, we review liquid-phase syntheses for the preparation of sulfide-based solid electrolytes and composites of electrolytes and electrodes, and we compare the charge–discharge performances of the all-solid-state lithium batteries using these components. The high lithium-ion conductivity and deformability of solid sulfide electrolytes make them key materials in all-solid-state lithium batteries. Liquid-phase reactions are valid and scalable approaches for the preparation of sulfide-based solid electrolytes that overcome the issues of moisture sensitivity and high vapour pressures of sulfur species.